{
  "bibcode": "2017GCN.20806....1T",
  "body": "A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,\nM. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline\non behalf of the Konus-Wind team, report:\n\nThe long-duration, hard-spectrum GRB 170228A\n(Fermi-LAT detection: Bissaldi et al., GCN 20785;\nFermi GBM observation: Veres et al., GCN 20786;\nAstroSat CZTI detection: Sharma et al., GCN 20788)\ntriggered Konus-Wind at T0=68584.788 s UT (19:03:04.788).\n\nThe burst light curve starts with a bright FRED-like pulse having a\nduration of ~20 s, followed by a weaker emission,\nwhich is detectable until ~T0+100 s.\nThe emission is seen up to ~3 MeV.\n\nAs observed by Konus-Wind, the burst\nhad a fluence of 4.99(-0.99,+1.51)x10^-5 erg/cm2,\nand a 64-ms peak energy flux, measured from T0+0.316 s,\nof 8.97(-2.47,+2.57)x10^-6 erg/cm2/s\n(both in the 20 keV - 10 MeV energy range).\n\nThe time-integrated spectrum of the burst\n(measured from T0 to T0+98.560 s)\nis best fit in the 20 keV - 15 MeV range\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith  alpha = -1.03(-0.18,+0.22),\nand Ep = 1017(-317,+657) keV (chi2 = 97/98 dof).\nFitting by the GRB (Band) model yields the same alpha and Ep,\nand an upper limit on the high energy photon index:\nbeta < -1.98 (chi2 = 97/97 dof).\n\nThe spectrum near the peak count rate\n(measured from T0 to T0+8.448 s)\nis best fit in the 20 keV - 5 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.43(-0.14,+0.17),\nthe high energy photon index beta = -2.78(-2.28,+0.48),\nthe peak energy Ep = 675(-92,+112) keV,\nchi2 = 95/76 dof.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB170228_T68584/\n\nAll the quoted errors are at the 90% confidence level.\nAll the quoted values are preliminary.",
  "circularId": 20806,
  "createdOn": 1488548960000,
  "email": "tsvetkova@mail.ioffe.ru",
  "subject": "Konus-Wind observation of GRB 170228A",
  "submitter": "Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>",
  "eventId": "GRB 170228A"
}